Advanced Size Mapping Module bug empties config on refresh

[benjaminclot]

Type of issue

When a config has an empty sizeConfig.sizes property set, [] becomes [[]] so on the next refresh, this adunit's sizeConfig becomes invalid and it gets "deleted". I have been able to trace the problem back to this test: https://github.com/prebid/Prebid.js/blob/master/modules/sizeMappingV2.js#L109

Test page

https://jsfiddle.net/Lmw0zrp5/
Have the window below 768px and hit refresh, pbjs.adUnits[0] will have its bids and mediaTypes properties empty.

Expected results

The pbjs.adUnits object should remain untouched or maybe the test should use utils.isEmpty()?

[Fawke]

Hi @benjaminclot,

Yeah, I see can that I'm getting an error on clicking "REFRESH" on your test page. Thanks for bringing this up, I think I've come up with a fix, and am working on some other optimizations, will raise a PR for this fix shortly.